// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <algorithm>

#include "build/build_config.h"
#include "skia/ext/convolver.h"
#include "skia/ext/convolver_SSE2.h"
#include "third_party/skia/include/core/SkTypes.h"

#include <emmintrin.h> // ARCH_CPU_X86_FAMILY was defined in build/config.h

namespace skia {

// Convolves horizontally along a single row. The row data is given in
// |src_data| and continues for the num_values() of the filter.
void ConvolveHorizontally_SSE2(const unsigned char* src_data,
    const ConvolutionFilter1D& filter,
    unsigned char* out_row,
    bool /*has_alpha*/)
{
    int num_values = filter.num_values();

    int filter_offset, filter_length;
    __m128i zero = _mm_setzero_si128();
    __m128i mask[4];
    // |mask| will be used to decimate all extra filter coefficients that are
    // loaded by SIMD when |filter_length| is not divisible by 4.
    // mask[0] is not used in following algorithm.
    mask[1] = _mm_set_epi16(0, 0, 0, 0, 0, 0, 0, -1);
    mask[2] = _mm_set_epi16(0, 0, 0, 0, 0, 0, -1, -1);
    mask[3] = _mm_set_epi16(0, 0, 0, 0, 0, -1, -1, -1);

    // Output one pixel each iteration, calculating all channels (RGBA) together.
    for (int out_x = 0; out_x < num_values; out_x++) {
        const ConvolutionFilter1D::Fixed* filter_values = filter.FilterForValue(out_x, &filter_offset, &filter_length);

        __m128i accum = _mm_setzero_si128();

        // Compute the first pixel in this row that the filter affects. It will
        // touch |filter_length| pixels (4 bytes each) after this.
        const __m128i* row_to_filter = reinterpret_cast<const __m128i*>(&src_data[filter_offset << 2]);

        // We will load and accumulate with four coefficients per iteration.
        for (int filter_x = 0; filter_x < (filter_length>> 2); filter_x++) {

            // Load 4 coefficients => duplicate 1st and 2nd of them for all channels.
            __m128i coeff, coeff16;
            // [16] xx xx xx xx c3 c2 c1 c0
            coeff = _mm_loadl_epi64(reinterpret_cast<const __m128i*>(filter_values));
            // [16] xx xx xx xx c1 c1 c0 c0
            coeff16 = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(1, 1, 0, 0));
            // [16] c1 c1 c1 c1 c0 c0 c0 c0
            coeff16 = _mm_unpacklo_epi16(coeff16, coeff16);

            // Load four pixels => unpack the first two pixels to 16 bits =>
            // multiply with coefficients => accumulate the convolution result.
            // [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
            __m128i src8 = _mm_loadu_si128(row_to_filter);
            // [16] a1 b1 g1 r1 a0 b0 g0 r0
            __m128i src16 = _mm_unpacklo_epi8(src8, zero);
            __m128i mul_hi = _mm_mulhi_epi16(src16, coeff16);
            __m128i mul_lo = _mm_mullo_epi16(src16, coeff16);
            // [32]  a0*c0 b0*c0 g0*c0 r0*c0
            __m128i t = _mm_unpacklo_epi16(mul_lo, mul_hi);
            accum = _mm_add_epi32(accum, t);
            // [32]  a1*c1 b1*c1 g1*c1 r1*c1
            t = _mm_unpackhi_epi16(mul_lo, mul_hi);
            accum = _mm_add_epi32(accum, t);

            // Duplicate 3rd and 4th coefficients for all channels =>
            // unpack the 3rd and 4th pixels to 16 bits => multiply with coefficients
            // => accumulate the convolution results.
            // [16] xx xx xx xx c3 c3 c2 c2
            coeff16 = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(3, 3, 2, 2));
            // [16] c3 c3 c3 c3 c2 c2 c2 c2
            coeff16 = _mm_unpacklo_epi16(coeff16, coeff16);
            // [16] a3 g3 b3 r3 a2 g2 b2 r2
            src16 = _mm_unpackhi_epi8(src8, zero);
            mul_hi = _mm_mulhi_epi16(src16, coeff16);
            mul_lo = _mm_mullo_epi16(src16, coeff16);
            // [32]  a2*c2 b2*c2 g2*c2 r2*c2
            t = _mm_unpacklo_epi16(mul_lo, mul_hi);
            accum = _mm_add_epi32(accum, t);
            // [32]  a3*c3 b3*c3 g3*c3 r3*c3
            t = _mm_unpackhi_epi16(mul_lo, mul_hi);
            accum = _mm_add_epi32(accum, t);

            // Advance the pixel and coefficients pointers.
            row_to_filter += 1;
            filter_values += 4;
        }

        // When |filter_length| is not divisible by 4, we need to decimate some of
        // the filter coefficient that was loaded incorrectly to zero; Other than
        // that the algorithm is same with above, exceot that the 4th pixel will be
        // always absent.
        int r = filter_length & 3;
        if (r) {
            // Note: filter_values must be padded to align_up(filter_offset, 8).
            __m128i coeff, coeff16;
            coeff = _mm_loadl_epi64(reinterpret_cast<const __m128i*>(filter_values));
            // Mask out extra filter taps.
            coeff = _mm_and_si128(coeff, mask[r]);
            coeff16 = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(1, 1, 0, 0));
            coeff16 = _mm_unpacklo_epi16(coeff16, coeff16);

            // Note: line buffer must be padded to align_up(filter_offset, 16).
            // We resolve this by use C-version for the last horizontal line.
            __m128i src8 = _mm_loadu_si128(row_to_filter);
            __m128i src16 = _mm_unpacklo_epi8(src8, zero);
            __m128i mul_hi = _mm_mulhi_epi16(src16, coeff16);
            __m128i mul_lo = _mm_mullo_epi16(src16, coeff16);
            __m128i t = _mm_unpacklo_epi16(mul_lo, mul_hi);
            accum = _mm_add_epi32(accum, t);
            t = _mm_unpackhi_epi16(mul_lo, mul_hi);
            accum = _mm_add_epi32(accum, t);

            src16 = _mm_unpackhi_epi8(src8, zero);
            coeff16 = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(3, 3, 2, 2));
            coeff16 = _mm_unpacklo_epi16(coeff16, coeff16);
            mul_hi = _mm_mulhi_epi16(src16, coeff16);
            mul_lo = _mm_mullo_epi16(src16, coeff16);
            t = _mm_unpacklo_epi16(mul_lo, mul_hi);
            accum = _mm_add_epi32(accum, t);
        }

        // Shift right for fixed point implementation.
        accum = _mm_srai_epi32(accum, ConvolutionFilter1D::kShiftBits);

        // Packing 32 bits |accum| to 16 bits per channel (signed saturation).
        accum = _mm_packs_epi32(accum, zero);
        // Packing 16 bits |accum| to 8 bits per channel (unsigned saturation).
        accum = _mm_packus_epi16(accum, zero);

        // Store the pixel value of 32 bits.
        *(reinterpret_cast<int*>(out_row)) = _mm_cvtsi128_si32(accum);
        out_row += 4;
    }
}

// Convolves horizontally along four rows. The row data is given in
// |src_data| and continues for the num_values() of the filter.
// The algorithm is almost same as |ConvolveHorizontally_SSE2|. Please
// refer to that function for detailed comments.
void Convolve4RowsHorizontally_SSE2(const unsigned char* src_data[4],
    const ConvolutionFilter1D& filter,
    unsigned char* out_row[4])
{
    int num_values = filter.num_values();

    int filter_offset, filter_length;
    __m128i zero = _mm_setzero_si128();
    __m128i mask[4];
    // |mask| will be used to decimate all extra filter coefficients that are
    // loaded by SIMD when |filter_length| is not divisible by 4.
    // mask[0] is not used in following algorithm.
    mask[1] = _mm_set_epi16(0, 0, 0, 0, 0, 0, 0, -1);
    mask[2] = _mm_set_epi16(0, 0, 0, 0, 0, 0, -1, -1);
    mask[3] = _mm_set_epi16(0, 0, 0, 0, 0, -1, -1, -1);

    // Output one pixel each iteration, calculating all channels (RGBA) together.
    for (int out_x = 0; out_x < num_values; out_x++) {
        const ConvolutionFilter1D::Fixed* filter_values = filter.FilterForValue(out_x, &filter_offset, &filter_length);

        // four pixels in a column per iteration.
        __m128i accum0 = _mm_setzero_si128();
        __m128i accum1 = _mm_setzero_si128();
        __m128i accum2 = _mm_setzero_si128();
        __m128i accum3 = _mm_setzero_si128();
        int start = (filter_offset << 2);
        // We will load and accumulate with four coefficients per iteration.
        for (int filter_x = 0; filter_x < (filter_length >> 2); filter_x++) {
            __m128i coeff, coeff16lo, coeff16hi;
            // [16] xx xx xx xx c3 c2 c1 c0
            coeff = _mm_loadl_epi64(reinterpret_cast<const __m128i*>(filter_values));
            // [16] xx xx xx xx c1 c1 c0 c0
            coeff16lo = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(1, 1, 0, 0));
            // [16] c1 c1 c1 c1 c0 c0 c0 c0
            coeff16lo = _mm_unpacklo_epi16(coeff16lo, coeff16lo);
            // [16] xx xx xx xx c3 c3 c2 c2
            coeff16hi = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(3, 3, 2, 2));
            // [16] c3 c3 c3 c3 c2 c2 c2 c2
            coeff16hi = _mm_unpacklo_epi16(coeff16hi, coeff16hi);

            __m128i src8, src16, mul_hi, mul_lo, t;

#define ITERATION(src, accum)                                      \
    src8 = _mm_loadu_si128(reinterpret_cast<const __m128i*>(src)); \
    src16 = _mm_unpacklo_epi8(src8, zero);                         \
    mul_hi = _mm_mulhi_epi16(src16, coeff16lo);                    \
    mul_lo = _mm_mullo_epi16(src16, coeff16lo);                    \
    t = _mm_unpacklo_epi16(mul_lo, mul_hi);                        \
    accum = _mm_add_epi32(accum, t);                               \
    t = _mm_unpackhi_epi16(mul_lo, mul_hi);                        \
    accum = _mm_add_epi32(accum, t);                               \
    src16 = _mm_unpackhi_epi8(src8, zero);                         \
    mul_hi = _mm_mulhi_epi16(src16, coeff16hi);                    \
    mul_lo = _mm_mullo_epi16(src16, coeff16hi);                    \
    t = _mm_unpacklo_epi16(mul_lo, mul_hi);                        \
    accum = _mm_add_epi32(accum, t);                               \
    t = _mm_unpackhi_epi16(mul_lo, mul_hi);                        \
    accum = _mm_add_epi32(accum, t)

            ITERATION(src_data[0] + start, accum0);
            ITERATION(src_data[1] + start, accum1);
            ITERATION(src_data[2] + start, accum2);
            ITERATION(src_data[3] + start, accum3);

            start += 16;
            filter_values += 4;
        }

        int r = filter_length & 3;
        if (r) {
            // Note: filter_values must be padded to align_up(filter_offset, 8);
            __m128i coeff;
            coeff = _mm_loadl_epi64(reinterpret_cast<const __m128i*>(filter_values));
            // Mask out extra filter taps.
            coeff = _mm_and_si128(coeff, mask[r]);

            __m128i coeff16lo = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(1, 1, 0, 0));
            /* c1 c1 c1 c1 c0 c0 c0 c0 */
            coeff16lo = _mm_unpacklo_epi16(coeff16lo, coeff16lo);
            __m128i coeff16hi = _mm_shufflelo_epi16(coeff, _MM_SHUFFLE(3, 3, 2, 2));
            coeff16hi = _mm_unpacklo_epi16(coeff16hi, coeff16hi);

            __m128i src8, src16, mul_hi, mul_lo, t;

            ITERATION(src_data[0] + start, accum0);
            ITERATION(src_data[1] + start, accum1);
            ITERATION(src_data[2] + start, accum2);
            ITERATION(src_data[3] + start, accum3);
        }

        accum0 = _mm_srai_epi32(accum0, ConvolutionFilter1D::kShiftBits);
        accum0 = _mm_packs_epi32(accum0, zero);
        accum0 = _mm_packus_epi16(accum0, zero);
        accum1 = _mm_srai_epi32(accum1, ConvolutionFilter1D::kShiftBits);
        accum1 = _mm_packs_epi32(accum1, zero);
        accum1 = _mm_packus_epi16(accum1, zero);
        accum2 = _mm_srai_epi32(accum2, ConvolutionFilter1D::kShiftBits);
        accum2 = _mm_packs_epi32(accum2, zero);
        accum2 = _mm_packus_epi16(accum2, zero);
        accum3 = _mm_srai_epi32(accum3, ConvolutionFilter1D::kShiftBits);
        accum3 = _mm_packs_epi32(accum3, zero);
        accum3 = _mm_packus_epi16(accum3, zero);

        *(reinterpret_cast<int*>(out_row[0])) = _mm_cvtsi128_si32(accum0);
        *(reinterpret_cast<int*>(out_row[1])) = _mm_cvtsi128_si32(accum1);
        *(reinterpret_cast<int*>(out_row[2])) = _mm_cvtsi128_si32(accum2);
        *(reinterpret_cast<int*>(out_row[3])) = _mm_cvtsi128_si32(accum3);

        out_row[0] += 4;
        out_row[1] += 4;
        out_row[2] += 4;
        out_row[3] += 4;
    }
}

// Does vertical convolution to produce one output row. The filter values and
// length are given in the first two parameters. These are applied to each
// of the rows pointed to in the |source_data_rows| array, with each row
// being |pixel_width| wide.
//
// The output must have room for |pixel_width * 4| bytes.
template <bool has_alpha>
void ConvolveVertically_SSE2(const ConvolutionFilter1D::Fixed* filter_values,
    int filter_length,
    unsigned char* const* source_data_rows,
    int pixel_width,
    unsigned char* out_row)
{
    int width = pixel_width & ~3;

    __m128i zero = _mm_setzero_si128();
    __m128i accum0, accum1, accum2, accum3, coeff16;
    const __m128i* src;
    // Output four pixels per iteration (16 bytes).
    for (int out_x = 0; out_x < width; out_x += 4) {

        // Accumulated result for each pixel. 32 bits per RGBA channel.
        accum0 = _mm_setzero_si128();
        accum1 = _mm_setzero_si128();
        accum2 = _mm_setzero_si128();
        accum3 = _mm_setzero_si128();

        // Convolve with one filter coefficient per iteration.
        for (int filter_y = 0; filter_y < filter_length; filter_y++) {

            // Duplicate the filter coefficient 8 times.
            // [16] cj cj cj cj cj cj cj cj
            coeff16 = _mm_set1_epi16(filter_values[filter_y]);

            // Load four pixels (16 bytes) together.
            // [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
            src = reinterpret_cast<const __m128i*>(
                &source_data_rows[filter_y][out_x << 2]);
            __m128i src8 = _mm_loadu_si128(src);

            // Unpack 1st and 2nd pixels from 8 bits to 16 bits for each channels =>
            // multiply with current coefficient => accumulate the result.
            // [16] a1 b1 g1 r1 a0 b0 g0 r0
            __m128i src16 = _mm_unpacklo_epi8(src8, zero);
            __m128i mul_hi = _mm_mulhi_epi16(src16, coeff16);
            __m128i mul_lo = _mm_mullo_epi16(src16, coeff16);
            // [32] a0 b0 g0 r0
            __m128i t = _mm_unpacklo_epi16(mul_lo, mul_hi);
            accum0 = _mm_add_epi32(accum0, t);
            // [32] a1 b1 g1 r1
            t = _mm_unpackhi_epi16(mul_lo, mul_hi);
            accum1 = _mm_add_epi32(accum1, t);

            // Unpack 3rd and 4th pixels from 8 bits to 16 bits for each channels =>
            // multiply with current coefficient => accumulate the result.
            // [16] a3 b3 g3 r3 a2 b2 g2 r2
            src16 = _mm_unpackhi_epi8(src8, zero);
            mul_hi = _mm_mulhi_epi16(src16, coeff16);
            mul_lo = _mm_mullo_epi16(src16, coeff16);
            // [32] a2 b2 g2 r2
            t = _mm_unpacklo_epi16(mul_lo, mul_hi);
            accum2 = _mm_add_epi32(accum2, t);
            // [32] a3 b3 g3 r3
            t = _mm_unpackhi_epi16(mul_lo, mul_hi);
            accum3 = _mm_add_epi32(accum3, t);
        }

        // Shift right for fixed point implementation.
        accum0 = _mm_srai_epi32(accum0, ConvolutionFilter1D::kShiftBits);
        accum1 = _mm_srai_epi32(accum1, ConvolutionFilter1D::kShiftBits);
        accum2 = _mm_srai_epi32(accum2, ConvolutionFilter1D::kShiftBits);
        accum3 = _mm_srai_epi32(accum3, ConvolutionFilter1D::kShiftBits);

        // Packing 32 bits |accum| to 16 bits per channel (signed saturation).
        // [16] a1 b1 g1 r1 a0 b0 g0 r0
        accum0 = _mm_packs_epi32(accum0, accum1);
        // [16] a3 b3 g3 r3 a2 b2 g2 r2
        accum2 = _mm_packs_epi32(accum2, accum3);

        // Packing 16 bits |accum| to 8 bits per channel (unsigned saturation).
        // [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
        accum0 = _mm_packus_epi16(accum0, accum2);

        if (has_alpha) {
            // Compute the max(ri, gi, bi) for each pixel.
            // [8] xx a3 b3 g3 xx a2 b2 g2 xx a1 b1 g1 xx a0 b0 g0
            __m128i a = _mm_srli_epi32(accum0, 8);
            // [8] xx xx xx max3 xx xx xx max2 xx xx xx max1 xx xx xx max0
            __m128i b = _mm_max_epu8(a, accum0); // Max of r and g.
            // [8] xx xx a3 b3 xx xx a2 b2 xx xx a1 b1 xx xx a0 b0
            a = _mm_srli_epi32(accum0, 16);
            // [8] xx xx xx max3 xx xx xx max2 xx xx xx max1 xx xx xx max0
            b = _mm_max_epu8(a, b); // Max of r and g and b.
            // [8] max3 00 00 00 max2 00 00 00 max1 00 00 00 max0 00 00 00
            b = _mm_slli_epi32(b, 24);

            // Make sure the value of alpha channel is always larger than maximum
            // value of color channels.
            accum0 = _mm_max_epu8(b, accum0);
        } else {
            // Set value of alpha channels to 0xFF.
            __m128i mask = _mm_set1_epi32(0xff000000);
            accum0 = _mm_or_si128(accum0, mask);
        }

        // Store the convolution result (16 bytes) and advance the pixel pointers.
        _mm_storeu_si128(reinterpret_cast<__m128i*>(out_row), accum0);
        out_row += 16;
    }

    // When the width of the output is not divisible by 4, We need to save one
    // pixel (4 bytes) each time. And also the fourth pixel is always absent.
    if (pixel_width & 3) {
        accum0 = _mm_setzero_si128();
        accum1 = _mm_setzero_si128();
        accum2 = _mm_setzero_si128();
        for (int filter_y = 0; filter_y < filter_length; ++filter_y) {
            coeff16 = _mm_set1_epi16(filter_values[filter_y]);
            // [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
            src = reinterpret_cast<const __m128i*>(
                &source_data_rows[filter_y][width << 2]);
            __m128i src8 = _mm_loadu_si128(src);
            // [16] a1 b1 g1 r1 a0 b0 g0 r0
            __m128i src16 = _mm_unpacklo_epi8(src8, zero);
            __m128i mul_hi = _mm_mulhi_epi16(src16, coeff16);
            __m128i mul_lo = _mm_mullo_epi16(src16, coeff16);
            // [32] a0 b0 g0 r0
            __m128i t = _mm_unpacklo_epi16(mul_lo, mul_hi);
            accum0 = _mm_add_epi32(accum0, t);
            // [32] a1 b1 g1 r1
            t = _mm_unpackhi_epi16(mul_lo, mul_hi);
            accum1 = _mm_add_epi32(accum1, t);
            // [16] a3 b3 g3 r3 a2 b2 g2 r2
            src16 = _mm_unpackhi_epi8(src8, zero);
            mul_hi = _mm_mulhi_epi16(src16, coeff16);
            mul_lo = _mm_mullo_epi16(src16, coeff16);
            // [32] a2 b2 g2 r2
            t = _mm_unpacklo_epi16(mul_lo, mul_hi);
            accum2 = _mm_add_epi32(accum2, t);
        }

        accum0 = _mm_srai_epi32(accum0, ConvolutionFilter1D::kShiftBits);
        accum1 = _mm_srai_epi32(accum1, ConvolutionFilter1D::kShiftBits);
        accum2 = _mm_srai_epi32(accum2, ConvolutionFilter1D::kShiftBits);
        // [16] a1 b1 g1 r1 a0 b0 g0 r0
        accum0 = _mm_packs_epi32(accum0, accum1);
        // [16] a3 b3 g3 r3 a2 b2 g2 r2
        accum2 = _mm_packs_epi32(accum2, zero);
        // [8] a3 b3 g3 r3 a2 b2 g2 r2 a1 b1 g1 r1 a0 b0 g0 r0
        accum0 = _mm_packus_epi16(accum0, accum2);
        if (has_alpha) {
            // [8] xx a3 b3 g3 xx a2 b2 g2 xx a1 b1 g1 xx a0 b0 g0
            __m128i a = _mm_srli_epi32(accum0, 8);
            // [8] xx xx xx max3 xx xx xx max2 xx xx xx max1 xx xx xx max0
            __m128i b = _mm_max_epu8(a, accum0); // Max of r and g.
            // [8] xx xx a3 b3 xx xx a2 b2 xx xx a1 b1 xx xx a0 b0
            a = _mm_srli_epi32(accum0, 16);
            // [8] xx xx xx max3 xx xx xx max2 xx xx xx max1 xx xx xx max0
            b = _mm_max_epu8(a, b); // Max of r and g and b.
            // [8] max3 00 00 00 max2 00 00 00 max1 00 00 00 max0 00 00 00
            b = _mm_slli_epi32(b, 24);
            accum0 = _mm_max_epu8(b, accum0);
        } else {
            __m128i mask = _mm_set1_epi32(0xff000000);
            accum0 = _mm_or_si128(accum0, mask);
        }

        for (int out_x = width; out_x < pixel_width; out_x++) {
            *(reinterpret_cast<int*>(out_row)) = _mm_cvtsi128_si32(accum0);
            accum0 = _mm_srli_si128(accum0, 4);
            out_row += 4;
        }
    }
}

void ConvolveVertically_SSE2(const ConvolutionFilter1D::Fixed* filter_values,
    int filter_length,
    unsigned char* const* source_data_rows,
    int pixel_width,
    unsigned char* out_row,
    bool has_alpha)
{
    if (has_alpha) {
        ConvolveVertically_SSE2<true>(filter_values,
            filter_length,
            source_data_rows,
            pixel_width,
            out_row);
    } else {
        ConvolveVertically_SSE2<false>(filter_values,
            filter_length,
            source_data_rows,
            pixel_width,
            out_row);
    }
}

} // namespace skia
